Cutter bit and support therefor



Nov. 13, 1962 c. F. osGooD CUTTER BIT AND SUPPORT THEREFOR Filed Nov. 9.1959 ,Avy

INVENTORZ United States Sal-639391 CUTTER BIT AND SUFFUR'I TIEREFRChartes F. sgood, Franklin, Pa., assigner to .loy Manufacturing Company,Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 9, 1959, Ser.No. 351,875 l Claims. ((11. 262-33) desirable to hold resiliently thecutter bit in cutting posi-l tion and to enable ready release of thebits from their supports by a relatively simple prying action. rthis issometimes accomplished by yieldable holding means on the supportengaging the shank of the cutter bit and yieldable to release itsholding action as the bit shank is pried out from the support socket.The present invention contemplates improvements over known types ofcutter bits and bit supports in that the resilient detent means servenot only to hold the cutter bit in cutting position on its support butalso locks the bit shank against rotation on its socket of support. Thebit support, in accordance with the present invention, may be either achain block of en-dless cutter chain or the supporting arm of a rotaryboring head, and desirably the `cutter bit has a cylindrical shankreceived in a socket of circular cross section, and the resilient detentmeans engages a recess in the bit shank not only to hold the sameagainst outward axial displacement but also to lock the bit shankagainst rotation in its socket.

It is therefore a primary object of the present invention to provide acutter bit and support therefor, having improved resilient detent meansengaging the bit shank for holding the cutter bit in cuttingy positionon its support. Another object is to provide an improved resilientdetent means for a cutter bit for locking the bit shank against rotationin the support socket. Yet another object is to provide a detent elementyieldingly mounted in a resilient mass of elastomeric material such asrubber supported within a transverse bore in the bit support and havinga detent portion yieldingly engaged in a recess in the bit shank. Yetanother object is to provide an improved cut ter bit of the cylindricalshank type having a longitudinal slot for receiving a detent element forlocking the cylindrical bit shank against outward axial displacementfrom and rotation in its socket. These and other objects and advantagesof the invention will however hereinafter more fully appear.

In the accompanying drawing there are shown for purposes of illustrationone preferred embodiment and a modification which the invention mayassume in practice.

In this drawing:

FIG. l is a fragmentary longitudinally extending verical section througha cutter bit support with a cutter bit mounted in cutting positionthereon and illustrating a preferred form of the improved resilientdetent means.

IFIG. 2 is a transverse section taken on line 2--2 of FIG. l.

FIG. 3 is a fragmentary section, taken in the plane of FIG. 1, showingthe cutter bit removed from the support socket and with the detent meansin released position.

FIG. 4 is a detail section taken on line 4 4 of FIG. 3.

FIG. 5 is a perspective view of the improved cutter bit.

FIG. 6 is a front elevational view of the cutter bit.

FIG. 7 is a detail section, similar to FIG. 3, with the bit shankpartially inserted in the support socket.

FIG. S is a detail section, similar to FIG. 7, showing the bit shankpartially released from its socket and with the detent held out of theshank-slot.

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FIG. 9 is a detail section, similar to FIG. 3, showing a slightlymodified mounting for the detent lock.

In the preferred illustrative construction, as shown in FIGS. 1 to 7inclusive of the drawing, a bit support l has a socket 2 of circularcross section for receiving the cylindrical shank 3 of a cutter bit 4.The bit support shown is desirably in the form of a chain block of aconventional `cutter chain but evidently the bit support may assumeother forms such as a supporting arm of a rotary boring head, in a wellknown manner. The cutter bit shank has an integral outer cutting portionor head 5 provided with a hard metal cutting point 6. The cutter headportion has a rearwardly located shoulder 7 seating at 8 against theouter portion of the support 1, as shown in FIG. l. A forwardly locatedshoulder l9 also on the bit head portion is engageable by a suitableprying instrument whereby the cutter bit may be removed with a pryingaction from the support socket.

The bit support has a forwardly located transverse bore it) in which aresilient mounting lll of the detent means is received. This resilientmounting desirably includes a resilient mass of elastomeric materialsuch as rubber in the form of a molded plug or block fitted within thetransverse bore, and the plug at its rearward side is cut away at 12 ona curve corresponding to the curvature of the adjacent socket wall (FIG.2). A detent element or latch 13 projects rearwardly into theshank-socket and has its transverse body portion 14 embedded in theelastic plug with its rearward detent or latch portion l5 received in alongitudinal slot or groove lo in the forward wall of the projectingdetent portion 1S of the detent element, and bit shank. This slotprovides a recess for receiving the the latter serves to hold the cutterbit in cutting position on its support, holding the bit shank bothagainst axial displacement frorn and rotation in the socket of itssupport. The resilient mounting for the detent also acts to some eX-tent as a cushion so that shocks and vibration are at least somewhatreduced.

The shank of the cutter bit at its inner portion is tapered at t7 toprovide an inclined surface which engages the I etent as the bit shankis inserted into the support socket (see FIG. 7) to tilt the detentoutwardly from the socket and when the slot lo assumes a position nearlyoppositely of the detent the detent element springs rearwardly with atilting motion and inwardly into the slot to hold the cutter bit inposition.

In the modification shown in FIG. 9 the elastic plug 18 is cut away orrecessed at i9 at its lower portion to provide a space into which theelastomeric material is squeezed as the detent is forced laterally uponmovement of the bit shank in the support socket. In FIG. 4 the ends ofthe elastic plug are desirably concaved at Zit so that when the detentis pressed laterally, as shown in FIGS. l and 2, the elastomericmaterial is forced or squeezed axially of the transverse bore to causethe concave ends of the plug to bulge outwardly as shown. Evidently theelastic plug may be held in position within the transverse bore in anysuitable manner.

As the bit shank is inserted into the support socket the inclined innersurface I7 of the shank engages the detent and forces the latterlaterally from the socket and tilts the detent inwardly and upwardly asshown in FIG. 8. When the slot 16 at the bit shank assumes a positionnearly opposite the detent the latter tilts back to its originalposition and is pressed inwardly by the resiliency of the elasticmounting into holding contact with the inclined bottom walls and sidesof the slot (FIG. l). The inner face of the detent is inclined at 2l toprovide a transverse edge 22 which engages the bottom walls of therecess lo at or near the point of convergence of the recess walls. Theshoulder 7 on the outer head portion of the cutter bit when the latteris in cutting position on its support rests at 8 against the outersurface of the support. The detent holds the bit shank against rotationin and outward axial displacement from the support socket with the headshoulder 7 maintained seated against the outer surfaces of the support.Upon withdrawal of the bit shank from the position shown in FIG. l, thelower inclined wall of the slot effects tilting of the detent back tothe position shown in FIG. 8, releasing the detent from the slot.

The cutter bit may be removed from its support by a prying action andthe forward shoulder 9 as on the outer head portion of the cutter bitmay be engaged by a suitable prying instrument for forcing the cutterbit outwardly from its support. As the bit shank is removed outwardlythe lower inclined bottom surface of the shank slot l tilts the detentlaterally from the slot thereby to release the bit shank for completefree withdrawal.

As a result of this invention an improved cutter bit and bit support areprovided having improved yieldable detent means for holding the cutterbit in cutting position on its support. The resilient detent means withits yieldably mounted detent element serves to hold the bit shank bothagainst outward axial displacement from and rotation in the supportsocket. The yieldable detent means enables ready release of the cutterbit from its support by a simple prying action thereby greatlyfacilitating bit replacement. tion will be clearly apparent to thoseskilled in the art.

While there are in this application specifically described one form anda modification which the invention may assume in practice, it will beunderstood that this form and modification thereof are shown forpurposes of illustra` tion and that the invention may be furthermodified and embodied in various other forms without departing from itsspirit or the scope of the appended claims.

What I claim as Vnew and desire to secure by Letters Patent is:

l. In a cutter bit and support therefor, a socket of circular crosssection formed in said support, a cutter bit having a lateral cuttingportion providing a forward cutting face, said bit also having acylindrical shank received and free to rotate in said socket with theshank substantially fitting the socket, said shank having a slotextending longitudinally along one side thereof, and resilient detentmeans carried by said support and projecting into said socket, saiddetent means having a detent element received in said shank-slot forholding said shank both against rotation in an axial displacement fromsaid socket, and resilient means for yieldingly urging said detentelement with a tilting motion into said slot in said bit shank, saidslot in said bit shank having relatively inclined con verging bottomWalls and said detent element being laterally tiltable about atransverse axis against the resilient action of said resilient means andhaving a portion seated in said slot against said bottom walls at ornear the point of convergence of said bottom walls, one of said wallsen- These and other advantages of the invenA gaging said detent elementupon movement of said shank A to tilt said detent element towardreleased position.

2. A cutter bit and support as set forth in claim 1 wherein saidtiltable detent element has an inner surface inclined inwardly toward asocket wall with said inner surface extending outwardly toward the outerend of said socket.

3. A cutter bit as set forth in claim 2 having inclined inner endsurface engageable with the inclined surface of said detent element forpressing the latter outwardly with a tilting action opposed by saidresilient means as said shank is inserted in said socket.

4. A cutter bit and support as set forth in claim 1 wherein the lowerinclined surface of said longitudinal shank slot engages the detentelement tilting the latter inwardly to effect lateral release of saiddetent element against the action of said resilient means as said bitshank is withdrawn by an axial prying action from said socket.

5. A cutter bit and support therefor comprising a socket in said supportfor receiving the shank of a cutter bit, said shank having an inclinedsurface at its inner portion, said support having a bore for receivingan elastic plug, a tiltable detent carried by said elastic plug andprojecting into said socket, said detent due to the elasticity of saidplug having a tilting motion relative to the bore walls, and a recess insaid bit shank disposed outwardly of said inclined shank surface intowhich said detent projects for holding said bit in cutting position onsaid support, said inclined surface on said bit shank as 4the latter isinserted in the socket pressing said detent outwardly and said detent bythe inherent resiliency of said elastic plug springing into said shankrecess when the latter is positioned oppositely of said detent, saidshank recess having an inclined bottom surface engaging said detent fortilting said detent outwardly toward released position in opposition tothe resilient action of said elastic plug as said bit shank is movedoutwardly in said socket.

6. A cutter bit `and support therefor, said support having a socket 0fcircular cross section and movable in a direction normal to the socketaxis, a cutter bit mounted on said support and having a lateral cuttingportion providing a front cutting face, said bit also having acylindrical shank receivable and freely rotatable in said socket, andresilient detent means on said support and comprising a detent elementproiecting into said socket at one wall thereof into engagement with thebit shank for locking the latter both against axial displacement fromand rotation in said socket, said shank having a slot extendinglongitudinally therealong midway between the sides of said cutter bitand positionable oppositely to said detent means, said slot havingparallel side walls and said detent element has a rectangular portionreceived in said slot and with which the parallel side walls of saidslot are tengageable, and an elastomeric plug arranged in a transversebore in said support and in which said detent element is embedded, saidplug acting as a spring for urging said detent element toward lockingposition, said plug holding said detent element when in locking positionagainst both lateral and outward movements.

7. A cutter bit and support as set forth in claim 6 wherein said slot islocated at the front side of said bit shank and said transverse boreenters said socket at the front side thereof and in which saidelastomeric plug is carried with said detent element projectingrearwardly from the front side of said bore into said slot.

8. A cutter bit and support as set forth in claim 6 wherein said slothas an inclined bottom surface engaging said detent element as said bitshank is withdrawn from said socket for effecting tilting of said detentelement about a transverse axis out of locking position and the inherentresiliency of said elastic plug permitting such tilt while always urgingsaid detent element toward locking position.

9. In a cutter bit and support therefor, said support having a socket, acutter bit having a shank fitted in said socket in engagement with thesocket walls, said'shank having a slot formed lengthwise thereof, saidsupport having a bore entering said socket, Van elastic plug held inposition in said bore, and a tiltable detent element embedded in saidelastic plug and urged inwardly thereby into said slot'for locking thecutter bit in cutting position on said support, said slot having aninclined bottom surface engaging said detent element for tilting saiddetent element relative to the bore-walls outwardly from said slot assaid shank is withdrawn from said socket and said elastic plug deformingto permit such outward tilting movement of said detent element and theinherent elasticity of said plug constantly urging said detent elementwith a tilting motion toward its inward locking position.

l0. In a cutter bit and support therefor, a socket of circular crosssection formed in said support, a cutter bit having a lateral cuttingportion providing a front cutting face and seated against said Support,said bit also having a cylindrical shank received and rotatable in saidsocket with said shank substantially fitting said socket, said shankhaving a slot extending longitudinally along one side thereof, saidsupport having a transverse bore entering said socket, a moldedresilient plug of elastomeric material secured in said bore, and adetent element ernbedded in said plug and engaging said shank-slot forholding said shank both against rotation in and axial displace ment fromsaid socket, said elastic plug yielding upon release of said detentelement from said slot in opposition to its inherent resiliency tendingto move said detent element toward locking position, said elastic plugalso resisting any tendency toward lateral movement of said detentelement to yieldingly oppose rotative movement of said shank in saidsocket.

References Cited in the tile of this patent UNITED STATES PATENTS722,324 Pitkin Mar. 10, 1903 2,610,049 Elles et al Sept. 9, 19522,907,559 Brown et al Oct. 6, 1959 2,965,365 Krekeler Dec. 20, 19602,996,291 Krekeler Aug. 15, 1961 FOREIGN PATENTS 743,234 Great BritainIan, 11, 1956

